This invention is directed to a sealed roller assembly for connecting link plates of a chain or a roller chain.
Chains and roller chains are commonly used to transfer torque from one gear sprocket to another gear sprocket, i.e., a motorcycle chain, or in conveyor-type systems to transport objects, i.e., conveyor belts. Roller chains are particularly useful for conveyor-type systems since roller chains utilize an additional roller which rotates while slidingly contacting guides for the roller chain. For example, roller chains can be used to propel traveling screens, which are used in the cooling inlets of electrical power generating stations to catch or remove objects, i.e., fish, seaweed, plants, and debris so that these objects do not enter the cooling station equipment. Such traveling screens consist of a series of screens, attached to roller chains, moving perpendicular to the cooling water inlet of the generating station. As the cooling water passes through the traveling screens, objects are trapped in the screens and are carried out of the water as the roller chain rotates so that the traveling screens can be cleaned.
Present chains and roller chains are subject to premature wear and chain failure due largely to contaminants, i.e., dirt, dust, sand and water between the rotating adjoining surfaces of the roller assemblies of the chain and/or poor lubrication between the rotating adjoining surfaces of the roller assemblies of the chain. Further, if the chain is operating in a harsh environment, such as ocean water, contaminants--i.e., salt water, sand, sea shells, dirt--quickly invade the rotating adjoining surfaces of the roller assemblies and remove the lubricant. Contaminants and lack of lubrication leads to increased friction and rapid wear of the rotating adjoining surfaces and, ultimately, chain failure.
With traveling screens, the roller chain failure typically occurs during storms when energy demands are critical, since the storms dislodge a large volume of objects which must be filtered from the cooling inlet of the generating station and the traveling screen must be operated for extended periods of time at increased loads and/or increased rotation speeds. The roller chain failure with traveling screens can cause cooling inlets to be closed and electrical power generating stations to operate at reduced capacity.
Presently, chains with some form of sealed roller assemblies are available in the marketplace. However, these chains do not provide an adequate seal for the roller assemblies in a harsh environment. Thus, the rotating adjoining surfaces become contaminated and the lubricant leaks from between these surfaces. Further, these chains do not provide a way to continuously resupply lubricant to the adjoining surfaces of the roller assemblies. Thus, the chain must be frequently relubricated manually.
Accordingly, there is a need for a chain utilizing sealed roller assemblies which prevents the influx of contaminants into the adjoining surfaces of the roller assemblies and provides a way to continuously lubricate the roller assemblies thereby reducing chain wear and reducing chain maintenance.